Effective temperature of detached eclipsing binaries from Hipparcos parallax

Effective temperatures of detached eclipsing binaries computed through Hipparcos trigonometric parallaxes are compared with the photometric determinations. The former are based on the values of the radius, the apparent visual magnitude and the bolometric correction of the star, whereas the latter are obtained from standard calibrations using Stromgren or Johnson colour indices. The working sample contains all well-studied detached double-lined eclipsing binaries belonging to the Hipparcos catalogue and with relative errors in the parallaxes smaller than 20%. They cover a temperature range from 5000 K to 25000 K. A small systematic trend of 0.010 dex (s.d. 0.010) for T-eff less than or equal to 10000 K and of 0.015 dex (s.d. 0.060) for T-eff > 10000 K is observed between the two temperature determinations, that could be due to inaccuracies on photometric effective temperatures.